The present invention relates generally to improvements in processing dairy whey and other protein sources for rendering them useful as a palatable extender, additive, product base, or protein supplement for a variety of food products. In its preferred form, the invention involves the maintenance of the whey by-product from a cheese-making operation at or near the temperature at which the whey is produced and power blending this hot by-product with a variety of substances in order to form a colloidal suspension including protein and naturally occurring sugars while eliminating characteristic whey odor and taste to form a useful and valuable colloidal protein source, while also simultaneously imparting a colloidal type of physical condition thereto for easy and rapid separation into a proteinaceous floc having a relatively high solids content and a proteinaceous liquid, both the floc and the liquid themselves also being palatable and useful in connection with food products, including the formation of a gelatin material that can be set at room temperature.
Over the years, numerous and varied approaches have been taken in an effort to transform large volumes of potentially valuable cheese-making whey by-products into products suitable for use within large-scale food processing operations. Whey by-products that fall within the general classification of sweet wheys are typically more palatable in the state in which they are formed and are generally more susceptible to treatment than are acid wheys. Sweet wheys are produced by the addition of proteolytic enzymes such as rennin and/or pepsin to milk in order to coagulate casein therewithin and form a cheese curd which is subsequently separated from the sweet whey thus produced as the uncoagulated, highly liquid whey by-product having a solids content of about 6.5 weight percent and which is all too often discarded as a waste product, sometimes to the detriment of the environment. Acid whey, which also has a solids content of about 6.5 weight percent, is formed during the production of products such as cottage cheese, made upon the coagulation of milk by the activity of a mineral acid or, more usually, by lactic acid produced bacteriologically.
Examples of the variety of attempts to transform large volumes of whey into products suitable for use within food processing are represented by Attebery U.S. Pat. No. 3,560,219, Wingerd U.S. Pat. No. 3,637,643, Eastman U.S. Pat. No. 3,842,062, and Grindstaff U.S. Pat. No. 4,036,999. Representative of literature in this area include: "Whey Products Conference/1974", Eastern Regional Research Center, U.S. Department of Agriculture, ERRC Publication No. 3996, April, 1975; and "Whey Products Conference/1976", Atlantic City, N. J., Eastern Regional Research Center, U.S. Department of Agriculture, ARS-NE-81, April, 1977. These various publications report upon a variety of previously known approaches taken in attempting to exploit the potential of whey as a source of high quality protein including virtually all of the amino acids and as a source of the minerals that are valuable to the maintenance of human health. A frequently sought after objective is the recovery of whey protein, as well as other protein such as soy protein, without its denaturation so that it can be readily combined with other food or feed components.
Raw whey itself has several properties that make it undesirable for use in food products, especially those for human consumption. Raw whey has a very pungent and generally undesirable odor and has taste characteristics that are equally unappealing. Raw whey also has a relatively high lactose to glucose ratio; typically raw whey contains no glucose, lactose being the only sweetness enhancer present. Lactose is not the most desirable form of sugar for most uses, it being much less sweet than, for example, glucose or galactose, both of which are known to be formed upon the hydrolysis of lactose. Known whey lactose hydrolysis methods have generally been restricted to either those using strong acid or those using enzymes of the lactose type. Acid hydrolysis typically requires very stringent conditions and results in significant denaturation of whey protein, making such an approach undesirable for producing valuable food products from whey. Enzyme hydrolysis has the serious disadvantage of requiring excessive lengths of time to perform the desired hydrolysis while requiring exacting biological conditions.
Numerous procedures are also available for the recovery of vegetable protein such as that found in soy beans or glutens. Most commercial sources of soy protein are extracted with hexane or other hydrophobic materials which impart hydrophobic tendencies to the extracted protein, thereby reducing the scope of usefulness for such proteins. Denaturation of vegetable protein while extracting it is also a significant problem.
Even were whey or vegetable protein to be treated successfully while avoiding protein denaturation, it typically has not heretofore been possible to readily separate solid fractions from liquid fractions. For example, in known whey treatment processes, when it is desired to recover whey solids or dewater the treated whey, difficult and usually less than adequate separation techniques must be employed, such as sophisticated high-speed centrifugation, molecular sieve operations such as those using ultrafiltration membranes, dialysis, electrodialysis, ion exchange resins, or other generally expensive procedures.
By the present invention, acid whey or sweet whey is rendered bland both from the point of view of odor and taste, is made more biologically stable, is improved in sweetness, and is reduced in lactose to glucose ratio, valuable results also being brought about for other protein sources, with all of these desirable properties being accomplished simultaneously while avoiding denaturation of the valuable protein and while placing the processed material into a form in which it can be readily separable into a solids fraction and a liquids fraction. Basically, the protein source is power blended in the presence of a component including a blandness imparting agent and a colloid enhancer.
It is a general object of the present invention to provide an improved protein product and process for forming it.
Another object of this invention is to provide an improved bland protein product from a pungent and often discarded protein source in order to prepare foods or feeds.
Another object of the present invention is to provide an improved protein product having a colloidal type of physical condition suitable for use in certain food applications while at the same time being ripe for further treatment in order to separate off a valuable proteinaceous floc from a valuable proteinaceous liquid, both being suitable for food uses.
Another object of this invention is an improved process and product produced thereby which avoids significant denaturation of protein from natural sources such as whey and vegetation.
Another object of this invention is an improved process for transforming cheese-making whey by-products into products suitable for use as palatable food extenders, additives, product bases or protein supplements.
Another object of the present invention is to provide an improved whey-based product having improved sweetness, a reduced lactose to glucose ratio, and enhanced biological stability, and a minimized manifestation of lactic acid.
Another object of the present invention is a substitute gelatin product and process of preparing same which incorporates a whey protein source.
Another object of this invention is to provide an improved product and process for washing whey from freshly produced cheese products.
These and other objects of this invention will be apparent from the following detailed description thereof.
In its basic embodiment, the present invention covers a process for treating protein sources with certain components, the use of those components for such purpose, and the products produced thereby. For convenience and for ease of reading, the descriptive portions of this specification discuss cheesemaking whey by-products as the source of protein, but the general principles of this invention are to be understood to be applicable to other protein sources, particularly vegetable protein sources, especially soy beans, or to animal sources other then whey.
Whey is power blended in the presence of a blandness imparting agent and a colloid enhancer to form a colloidal type of system. Such a system is then readily separable into a solids fraction or floc and a liquids fraction by the addition of a floc initiator. Other ingredients, for example a pH adjuster, an oxidizing agent, an enzyme, such as lactose, a colorant, a flavoring, a natural moss, or other type of ingredient may be added in order to impart certain properties to the formulations.
An important feature of this invention is the use of whey that is fresh as possible and that has not been permitted to cool down to a significant extent from the temperature at which the whey is generated in a cheese-making process. Less than completely fresh whey can be adequately processed in accordance with this invention provided its temperature is maintained as high as possible and preferably such that it does not drop below 90.degree. F., more preferably 100.degree. F. Usually, the more efficient the temperature maintenance and the shorter the time lapse between generation of the raw whey and its treatment in accordance with this process, the more valuable and more advantageous is the final product of this invention.
Blandness imparting agents in accordance with this invention are especially useful for masking or blanding the unpleasant odor and taste properties of natural protein sources, especially whey. They are also especially valuable within systems that exhibit colloidal tendencies. Metal gluconates are particularly useful in this regard, especially when provided in solution and in combination with an aminocarboxy acid, preferably aminoacetic acid or glycine. In an especially preferred embodiment, the blandness imparting agent is an aqueous solution containing a 1:1 molar combination of metal gluconate and glycine. Acceptable metal gluconates include iron or ferrous gluconate and copper gluconate. In the preferred embodiment, the 1:1 molar combined solution of metal gluconate and glycine is added in a total quantity of between about 5 ml to about 60 ml for each gallon (3.785 liters) of raw whey.
Colloidal enhancers in accordance with this invention belong to the general class of cellulose derivatives, particularly those of the cellulose glycolate type, most preferably a carboxyalkyl cellulose material, including alkali metal carboxymethyl cellulose compounds. The preferred colloidal enhancer is sodium carboxymethyl cellulose, also known as CMC. Useful in this regard are other synthetic or natural gums which have somewhat high viscosities and exhibit general protective colloid properties such as locust bean gum, guar gum, karaya gum, gum traq, or mixtures thereof. Quantities of the colloid enhancer may generally range between about 2 and about 40 grams for each gallon (3.785 liters) of liquid. When the colloid enhancer is subjected to power blending conditions in the presence of raw whey, especially raw whey already having the blandness imparting agent and a metal hydroxide blended therewith, it imparts to the whey a colloidal-type physical condition which renders the whey particularly susceptible to the operation of the floc initiator of this invention when it is included in order to form a solids fraction and a liquids fraction.
When floc initiator is to be used, it is preferably added after the blandness imparting agent, a metal hydroxide if used, and the colloid enhancer are all added, whereupon the whey product will, without any further treatment whatsoever, separate into the solids fraction and the liquids fraction, the solids fraction being in the form of a very thick floc from which the liquids fraction can be readily decanted by a separatory funnel apparatus, the volume of the solids fraction or floc being approximately the same as the volume of the liquids fraction. The floc initiator generally belongs to the class of alkali metal silicates, most advantageously provided in the form of highly alkaline sodium or potassium solutions, especially sodium silicate solutions which typically contain approximately 40% Na.sub.2 Si.sub.3 O.sub.7 and which can be represented by the formulation (SiO.sub.2 /Na.sub.2 O)=3.22. Floc initiator solution may be added in quantities between about 5 and about 60 ml for each gallon (3.785 liters) of raw whey, preferably between about 10 ml and about 40 ml.
An optional ingredient that can be added in accordance with this invention is a source of divalent metal ions, preferably calcium ions in the form of calcium hydroxide so as to serve to raise the pH of the raw whey while adding calcium ions thereto. From about 1 to about 15 grams of calcium hydroxide powder may be added to each gallon (3.785 liters) of raw whey, depending generally upon the pH of the raw whey as modified by the other materials added to the system. Preferably, the pH of the system after addition of the floc initiator will be at or near the isoelectric point of the whey proteins, which is typically at a slightly acidic pH, the isoelectric point of a typical cottage cheese whey protein makeup being between about 6.4 and 6.6. In some instances, such as when the protein source being treated is a sweet whey, the pH may have to be lowered somewhat through the use of an acid, preferably a weak, edible acid such as citric acid. In general, the quantity of any pH adjuster will be dictated by the amount needed to approximate the isoelectric point of the total system.
In some instances, it may be desirable to add an oxygen source with a view toward further enhancing the bacteriological preservation properties of the system above those provided by the blandness imparting agent. Ingredients such as hydrogen peroxide or sources of ozone bubbled into the system will generally improve the bacteriological stability thereof. Very small concentrations of these oxygen sources are adequate, for example between about 2 and about 15 ml of hydrogen peroxide can be added.
Although this invention is not to be limited by any theory of reaction mechanism or ionic equilibria analysis, the following explanations are offered. Blandness imparting agents such as the iron and copper gluconates in combinations with glycine which assists in keeping the metal ions in solution, when subjected to power blending that develops shear forces, and particularly when combined with the addition of calcium ions into the system as a next step, helps to develop the colloidal nature of the protein material in order to keep the various particles and ions well dispersed within the system in order to counteract whey protein membranes and combine with each other readily to effect the automatic decanting feature of this invention. It has been found, consistent with these explanations, that superior results are achieved when the blandness imparting agent is added first, optionally followed by calcium hydroxide, after which the colloidal enhancer is added, all while the power blending is being accomplished, after which adding the floc initiator will bring about floc formation within a matter of minutes or less.
It has been observed that protein denaturation is not significant and the ratio of lactose to glucose is decreased when the present invention is practiced. Typically, raw whey contains only lactose or milk sugar, which has a chemical structure including glucose and galactose molecules, both of which have greater sweetening attributes than lactose. During the high-shear dispersion of the materials in accordance with this invention, the overall sweetness of the product is enhanced significantly, and the ratio of lactose to glucose is found to decrease over that of the untreated raw product. In connection with enzyme lactose hydrolysis techniques, whey treated in accordance with this invention can be subjected to lactose conversion by using significantly reduced quantities of enzymes such as lactase.
It is further believed that when the floc initiator component is utilized, the colloidal enhancer moves substantially entirely into the liquids fraction, rather than into the floc or solids fraction, which enhances the usefulness of the liquids fraction as an important gelatin substitute. Upon the addition of a natural moss or a gum, it is believed to combine with the colloidal enhancer within the liquids fraction in order to form a high-protein gelatin type product which can set or gel under ambient temperature conditions above the refrigeration temperatures normally associated with the setting of gelatin. Generally, this gelatin formation occurs upon adding from about 10 to about 50 grams of a natural moss to a quantity of about 2,000 mls of the liquids fraction.
A typical processing sequence for transforming whey into palatable foods or food ingredients begins by maintaining the temperature of the whey to near but not significantly above the temperature at which it is discharged during a commercial cheese-making operation. This discharge temperature is below the temperature at which whey protein will denature and generally ranges between about 120.degree. and 125.degree.. The temperature should not be allowed to drop below about 90.degree. F. during any storage time, preferably being maintained well above 100.degree. F. Additionally, the effectiveness of this process can be greatly diminished due to what is believed to be breakdown of proteins within the whey environment if the temperature maintenance is allowed to continue for too long a period of time, for example in excess of eight hours.
Fresh, warm whey is then subjected to power blending conditions or other suitable means which will impart shear forces to the whey, preferably by passing the materials between rotating knife edges and by forming a vortex-like flow path within the power blender. These power blending conditions should be accompanied by steady heating if the whey is not warm enough. The temperature of the whey when being treated should generally be above 125.degree. F. and below the denaturing temperatures for the proteins present, preferably between about 130.degree. F. and 135.degree. F. Generally, the components added in accordance with this invention are blended in while the fresh whey is maintained at this temperature, with the floc initiator being added after the maximum temperature is reached and the blending being terminated when the temperature of the whey being treated reaches at least 125.degree. F.
Food products made in accordance with this invention can utilize the unseparated colloidal dispersion, the separated solids fraction, or the separated liquids fraction. The usefulness of the unseparated dispersion can be enhanced by homogenization either before or after incorporation into a food product such as flavored drinks, unflavored protein drinks of the soya milk type, or simulated whole milk dairy drinks using the whey material as an extender for skim milk. The separated liquids fraction, which may have been self-decanted from the solids fraction floc, may also be used in preparing these and other types of high moisture content products. Separated solids fraction, which may have been formed by automatic decanting from the liquids fraction, is more advantageously used within lower moisture content products such as ice cream, yogurt and creamy dressings such as those of the cottage cheese type. When appropriate to do so, any of these food products may be pasteurized in accordance with customary procedures.
A particularly advantageous use of the liquids fraction is in making a substitute gelatin that will set at room temperature or under refrigeration. A natural moss or gum, such as a sea moss, is incorporated into the liquids fraction, preferably under power blending or shear conditions. Gelatins made in this manner, however, tend to have a cloudy white or beige appearance, which is undesirable for adding simple coloring agents thereto. A clear product combines a soya-based protein extract liquid prepared according to the general principles of this invention with the separated whey liquids fraction.
More particularly, in preparing such a soya-whey gelatin product, a source of isolated protein, preferably one that had been extracted in a manner that does not form any significant residue of hydrophobic chemicals, is dispersed within distilled water, preferably under power blending or shear conditions according to this invention. In order to control the characteristic odor and taste of soy protein, thought to be caused by the presence of tannin, the addition of the blandness imparting agent in accordance with this invention is made, which may be followed by the addition of a pH adjuster. Blending is continued, and a dissolved enzyme such as papain is added in a quantity of between about 1 and 5 grams of enzyme per 2500 mls of water base, followed by the addition of between about 1 and about 10 ml of an emulsion having approximately equal volume amounts of carbon disulfide and of a food grade emulsifier. At this stage, immediate clarification of the material begins, and more complete clearing develops upon blending at ambient temperature for approximately one hour and standing for a few hours thereafter. When this product is combined with the liquids fraction from the decanted whey product, preferably again under power blending or shear conditions, a clear blend including undenatured protein is obtained. When a natural moss or gum is power blended thereinto, a material is formed, which, when allowed to stand at ambient temperature, will set into a clear gelatin mass having acceptable thermomeltability. Thereafter, the set product can be dried by following customary procedures, including passing through a votator type of blender or ricer under temperatures on the order of about 40.degree. to about 45.degree. F. followed by heat drying, usually under convexion conditions. It is believed that it might be advantageous to lower the pH of the blended whey-soya mixture and filter the mixture by electrophoresis or the like, and then again raise the pH to near the isoelectric point of the protein prior to adding the natural gum or moss in forming this gelatin product.
Blandness imparting agents as specified herein can also be useful within cheese making operations as a product for assisting in the final separation of whey from cheese during the production thereof. Approximately 10 to 20 ppm of the blandness imparting agents of this invention added to the final cheese rinsing water will improve this stage of cheese making.